Method __call__

src/werkzeug/middleware/shared_data.py:227–283

(
        self, environ: WSGIEnvironment, start_response: StartResponse
    )

        return f"wzsdm-{timestamp}-{file_size}-{checksum}"

    def __call__(
        self, environ: WSGIEnvironment, start_response: StartResponse
    ) -> t.Iterable[bytes]:
        path = get_path_info(environ)
        file_loader = None

        for search_path, loader in self.exports:
            if search_path == path:
                real_filename, file_loader = loader(None)

                if file_loader is not None:
                    break

            if not search_path.endswith("/"):
                search_path += "/"

            if path.startswith(search_path):
                real_filename, file_loader = loader(path[len(search_path) :])

                if file_loader is not None:
                    break

        if file_loader is None or not self.is_allowed(real_filename):  # type: ignore
            return self.app(environ, start_response)

        guessed_type = mimetypes.guess_type(real_filename)  # type: ignore
        mime_type = get_content_type(guessed_type[0] or self.fallback_mimetype, "utf-8")
        f, mtime, file_size = file_loader()

        headers = [("Date", http_date())]

        if self.cache:
            timeout = self.cache_timeout
            etag = self.generate_etag(mtime, file_size, real_filename)  # type: ignore
            headers += [
                ("Etag", f'"{etag}"'),
                ("Cache-Control", f"max-age={timeout}, public"),
            ]

            if not is_resource_modified(environ, etag, last_modified=mtime):
                f.close()
                start_response("304 Not Modified", headers)
                return []

            headers.append(("Expires", http_date(time() + timeout)))
        else:
            headers.append(("Cache-Control", "public"))

        headers.extend(
            (
                ("Content-Type", mime_type),
                ("Content-Length", str(file_size)),
                ("Last-Modified", http_date(mtime)),
            )
        )
        start_response("200 OK", headers)
        return wrap_file(environ, f)